1. Field of the Invention
The invention relates to a fluid purification system that is modular, easily modified and adapted to different installations, and can be serviced in a sanitary manner, without the need for service personnel to have contact with the filter media or filtered material thereon. The invention is particularly suitable for filtering water used in the beverage and food industries, e.g., for water purification at restaurants, hotels, and the like.
2. Description of Related Art
Conventional water purification installations for the food and beverage industry contain inflow piping, a purification head and sump, purification media disposed within the sump, and outflow piping. The purification head directs the inflowing water to a flow path typically between the sump and the purification media (often a cylindrical block of activated carbon particles bonded together with a polymeric binder resin, and having an opening along the longitudinal axis thereof). Water is forced through the purification media, and removed (e.g., by flow through the central opening thereof) through the outflow piping.
Typically, the sump and purification head are threaded together. Changing of the purification media cartridge is done by unscrewing the sump, pulling out the cartridge, inserting a new cartridge, and screwing the sump back on the purification head. This requires contact with the used cartridge, a potentially unsanitary condition, since these purification cartridges often remove microorganisms and heavy metals from the water. Moreover, improper replacement of the sump makes the system prone to leaking. Special tools are necessary to remove and replace the sump without leakage.
With conventional systems, the use of multiple purification media requires the use of multiple manifolds and purification heads and sumps, connected by piping and plumbing fittings, all of which are prone to leak, particularly as the system is stressed during maintenance and cartridge replacement. In addition, these systems are typically wall mounted, and require robust wall mounting hardware to support their weight and the stresses imposed by flow through the system, maintenance, etc. Parallel flow systems typically require a large number of pipe fittings and connections, which increase pressure drop in the system and decrease the maximum flow rate through the system. Often, these fittings are metallic, and can leach metal into the water, creating health and safety issues.
Conventional sump/purification head designs also are deficient in that they do not make full use of the purification media cartridge. Flow into the sump creates “dead zones” in the sump where flow does not reach, and concentrates flow in other areas of the sump. As a result, large areas of the purification media remain unused because unfiltered water does not contact them, while other areas become clogged or saturated with contaminants very rapidly, because all of the flow passes through them. This phenomenon significantly decreases the life of the filter media cartridge, requiring an increased level of maintenance, increased cost, and increased risk of health or safety issues to consumers.
Conventional purification systems also are designed with multiple and different internal diameters for various fittings, inlets, outlets, internal flow conduits, and other openings within the system. Typically, this inconsistency results in fluid passing from a larger diameter conduit, opening, or chamber, to a lower diameter opening; in effect, conventional purification systems require that the fluid pass through internal “orifices.” These orifices reduce the fluid conductance of the system, since each additional “orifice” added in series lowers the overall conductance of the system, in accordance with the formula:
      1          C      total        =            1              C        1              +          1              C        2              +    …    +          1              C        n            where Ctotal is the fluid conductance of the entire apparatus, C1 is the fluid conductance of the first orifice in the system, and Cn is the fluid conductance of the nth orifice in the system. Each orifice therefore reduces the flow rate through the system for a given pressure drop, according to the formula:Q=Ctotal(Pfinal−Pinitial)where Q is the flow rate through the system, Ctotal is the fluid conductance of the entire apparatus, and Pfinal−Pinitial is the pressure drop across the apparatus. Currently available filtration systems have sufficiently low fluid conductance that water filtration flow rates of only about 10 gpm (for a pressure drop of 10 psi) are obtained.
There remains a need in the art for a purification system that is flexible (e.g., that allows both serial and parallel flows through the same system without undue piping and pipe fittings), that is modular (e.g., that allows easy change out of purification media cartridges without the need for service personnel to have contact with contaminated purification media), that has a reduced pressure drop and increased maximum flow rate, and that does not suffer from the “dead zone” phenomenon (i.e., has increased cartridge life). Further, there is a need for systems that are easily assembled, require few or no metallic fittings or solder to corrode or leak, and are unlikely to leak. Finally, there is a need in the art for purification systems that can deliver much higher flow rates at acceptable pressure drops than are currently available in existing, conventional fluid purification systems.